System and method for real-time correlation of aal2 and aal5 messages for calls in utran

ABSTRACT

System and method for correlating multiple frames of data associated with a single call into a call record. One embodiment comprises correlating data in a radio access network by capturing data passing to and from a radio network controller, identifying ATM Adaptation Layer type 5 (AAL5) frames within the data, assigning a first call identifier to the AAL5 frames, identifying ATM Adaptation Layer type 2 (AAL2) frames within the data, assigning a second call identifier to the AAL2 frames, and combining AAL2 frames and AAL5 frames having a same first call identifier and a same second call identifier into a call record. The data passing to and from the first radio network controller may be data passing over an Iub interface between a Node B and the radio network controller or data passing over an Iur interface between two radio network controllers.

This application claims the benefit of U.S. Provisional Application No.60/909,295, filed on Mar. 30, 2007, entitled System and Method forReal-Time Correlation of AAL2 and AAL5 Messages for Calls in UTRAN,which application is hereby incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to a system and method formonitoring messages in a wireless system, and more particularly to asystem and method for capturing and correlating related messagescaptured from the Iub and Iur interfaces of a UTRAN.

BACKGROUND

The Universal Mobile Telecommunications System (UMTS) is athird-generation (3G) mobile phone technology standardized first by theEuropean Telecommunications Standards Institute (ETSI) and now by the3rd Generation Partnership Project (3GPP). UMTS carries both circuitswitched (CS) and packet switched (PS) traffic using Wideband CodeDivision Multiple Access (W-CDMA) as its air interface. The descriptionof the network components and protocols used in UMTS are well known tothose of ordinary skill in the art and are available to the public from3GPP, ETSI, and other sources. The UMTS network architecture consists ofthree domains: Core Network (CN), UMTS Terrestrial Radio Access Network(UTRAN), and User Equipment (UE).

The Core Network provides switching and routing for user traffic andprovides network management functions. The Core Network architecture isbased on the GSM network with GPRS. The UTRAN provides the air interfaceaccess to subscribers' UE. Base stations in the UTRAN are referred asNode-Bs, and the control equipment for the Node-Bs is called a RadioNetwork Controller (RNC). The UMTS User Equipment communicates via theWCDMA air interface to the Node-Bs. The UE may be attached to either thePS domain or CS domain or both. The UE is capable of simultaneouslyusing PS services and CS services.

The Asynchronous Transfer Mode (ATM) is used for data transmission inUMTS. The ATM layer multiplexes and demultiplexes and routes ATM cells,and ensures their sequence from end to end. The ATM Adaptation Layers(AAL) are responsible for the creation and reception of payloads throughthe lower layers of ATM on behalf of different applications. ATMAdaptation Layer type 2 (AAL2) handles circuit-switched connections andpacket connection protocol AAL5 is designed for data delivery.

One disadvantage of the prior art is the difficulty in evaluatingservice levels for individual subscribers. Because multiple UEs arecommunicating with Node Bs and RNCs at the same time, thousands of dataand control messages per second can be passed between a Node B and anRNC and between RNCs. These messages follow several different protocolformats depending upon the purpose of the message. As a result, themessages passing on interfaces in the UTRAN do not provide sufficientinformation to determine which messages are related to the samesubscriber.

A second disadvantage of the prior art is the lack of a capability tocompile messages for a specific UE call into a single call record inreal-time or near real-time.

SUMMARY OF THE INVENTION

These and other problems are generally solved or circumvented, andtechnical advantages are generally achieved, by embodiments of thepresent invention which provides a system and method for capturingmessages from the Iur and Iub interfaces in a UTRAN and correlating themessages into call records for each user.

In accordance with an embodiment of the present invention, a method forcorrelating data in a radio access network comprises capturing datapassing to and from a first radio network controller, identifying ATMAdaptation Layer type 5 (AAL5) frames within the data, assigning a firstcall identifier to the AAL5 frames, identifying ATM Adaptation Layertype 2 (AAL2) frames within the data, assigning a second call identifierto the AAL2 frames, and combining AAL2 frames and AAL5 frames having asame first call identifier and a same second call identifier into a callrecord. The data passing to and from the first radio network controllermay comprise data passing over an Iub interface between a Node B and thefirst radio network controller or data passing over an Iur interfacebetween the first radio network controller and a second radio networkcontroller. The call record comprises service data units (SDUs)associated with a single call. The method may further comprisedeciphering the AAL2 frames, and reassembling service data units (SDUs)carried in the AAL2 frames. Capturing data passing to and from a firstradio network controller may further comprise capturing data passingfrom the first radio network controller to a first base station that isin communication with user equipment, and capturing data passing fromthe first radio network controller to a second base station that is incommunication with the user equipment, wherein the first radio basestation and the second radio base station are in communication with theuser equipment at the same time.

In accordance with another embodiment of the present invention, a systemfor correlating data in a radio access network comprises a firstcorrelation engine coupled to interfaces between components of the radioaccess network, wherein the first correlation engine receives ATMAdaptation Layer type 2 (AAL2) frames and ATM Adaptation Layer type 5(AAL5) frames from the interfaces, a second correlation engine coupledto the first correlation engine, wherein the second correlation enginereceives AAL2 frames from the first correlation engine, and a thirdcorrelation engine coupled to both the first and second correlationengines, wherein the third correlation engine receives AAL5 framesmapped to a first call identifier from the first correlation engine andreceives AAL2 frames mapped to a second call identifier from the secondcorrelation engine. The second correlation engine may further comprise adecipher engine, wherein the decipher engine decodes and deciphers theAAL2 frames, and a reassembly engine, wherein the reassembly engineassembles data carried in the AAL2 frames into service data units(SDUs). The first correlation engine maps parameters of a Node BApplication Part (NBAP) protocol, a Access Link Control Application Part(ALCAP) protocol, and/or a Radio Network Subsystem Application Part(RNSAP) protocol to the first call identifier. The second correlationengine maps parameters of a Radio Resource Control (RRC) protocol to thesecond call identifier. The first correlation engine may be coupled toIub and Iur interfaces in a UTRAN.

In accordance with another embodiment of the present invention, one ormore processors running software applications may be used to correlatedata frames in a radio access network The system comprisescomputer-readable medium having computer-executable instructions forcombing data associated with calls in a radio access network, saidcomputer-executable instructions comprising means for capturing datafrom the radio access network, means for identifying ATM AdaptationLayer type 5 (AAL5) frames within the data, means for assigning a firstcall identifier to the AAL5 frames, means for identifying ATM AdaptationLayer type 2 (AAL2) frames within the data, means for assigning a secondcall identifier to the AAL2 frames, and means for combining AAL2 framesand AAL5 frames having a same first call identifier and a same secondcall identifier into a call record. The computer-readable medium furtherhas computer-executable instructions comprising means for capturing datapassing to and from a radio network controller over one or more Iubinterfaces and one or more Iur interfaces in the radio access network.The computer-executable instructions further comprise means fordeciphering the AAL2 frames, and means for reassembling service dataunits (SDUs) carried in the AAL2 frames. The computer-executableinstructions may further comprises means for capturing data passing froma first base station in the radio access network to user equipment, andmeans for capturing data passing from second base station in the radioaccess network to the user equipment.

The present invention allows a system to analyze network performance ona real-time or near real-time basis for specific calls and specificusers. The present invention also captures messages for a single callfrom multiple interfaces and compiles the messages having differentprotocols and formats into a call record for a specific user.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates monitoring equipment coupled to UMTS networkinterfaces according to embodiments of the invention;

FIG. 2 is a protocol stack for an Iub interface;

FIG. 3 is a protocol stack for an Iur interface;

FIG. 4 illustrates the relationship among different correlation enginesaccording to embodiments of the invention;

FIG. 5 illustrates a class diagram of an embodiment of a UTRAN RRCManager according to embodiments of the invention;

FIG. 6 illustrates the relationship between an RLC/MAC Reassembly Engineand correlation engines according to embodiments of the invention;

FIG. 7 illustrates the architecture of an RLC/MAC Reassembly Engineaccording to embodiments of the invention;

FIG. 8 is a class diagram of a RLC/MAC Reassembly Engine according toembodiments of the invention; and

FIG. 9 is a block diagram illustrating tracking of messages according toone embodiment of the invention.

DETAILED DESCRIPTION

The present invention provides many applicable inventive concepts thatcan be embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

FIG. 1 illustrates a portion of UTRAN 100 comprising Node B 101 andRadio Network Controllers (RNC) 102 and 103. Node B 101 communicateswith RNC 102 via Iub interface 104. RNCs 102 and 103 communicate witheach other via Iur interface 105. Node B 101 is in communication withUser Equipment (UE) 106. Whenever UE 106 makes or receives a call,signaling messages are exchanged between Node B 101 and RNC 102 over Iubinterface 104 and between RNCs 102 and 103 over Iur interface 105. Thepresent invention tracks protocol messages carried on interfaces 104 and105 using UTRAN monitoring equipment 107, which is non-intrusivelycoupled to the interfaces to capture substantially all of the protocolmessages traveling across the interfaces. UTRAN monitoring equipment 107identifies the messages belonging to a single call and correlates thosemessages into one call record for each call it detects.

FIG. 2 illustrates the protocol stack used on the Iub interface in aUTRAN network. FIG. 3 illustrates the protocol stack used on the Iurinterface in a UTRAN network. UTRAN implements an ATM infrastructure forthe Iub and Iur interfaces. UTRAN uses both AAL2 and AAL5 adaptations ontop of the ATM layer. Node B Application Part (NBAP), Access LinkControl Application Part (ALCAP) and Radio Network Subsystem ApplicationPart (RNSAP) protocol messages are carried over AAL5 channels, and(Radio Resource Control) RRC protocol messages are carried over AAL2channels.

In one embodiment of the invention, two correlation engines running inUTRAN monitoring equipment 107 correlate messages into call records.They are the UTRAN Call Id (CID) engine, an AAL5 correlator, and theUTRAN RRC manager, AAL2 correlator. The correlation engines may be, forexample, software applications running on a processor in monitoringequipment 107.

UTRAN CID Engine—Call Correlation

The UTRAN CID Engine assigns a unique call identifier (Call Id) to everyAAL5 message captured by UTRAN monitoring equipment 107. The Call Id isderived from the RNC identifier and the uplink scrambling code assignedto UE 106. The format of the AAL Call Id is as follows:

AAL5 Call Id format RNC Id Uplink Scrambling Code 4 bytes 4 bytes

All AAL5 messages belonging to the same call are associated to the sameuplink scrambling code and, therefore, will have the same AAL5 Call Id.Accordingly, all NBAP, ALCAP, and RNSAP protocol messages for a singlecall will have the same AAL5 Call Id. The UTRAN CID Engine correlatesthe various AAL5 protocols as follows.

NBAP Protocol Correlation

All call-based NBAP signaling begins with a NBAP Radio Link (RL) SetupRequest message, which is sent from RNC 102 to Node B 101. This messageincludes the uplink scrambling code assigned to UE 106. An AAL5 Call Idis generated and assigned to the NBAP RL Setup Request message. The NBAPRL Setup Request message also includes a Controlling RNC (CRNC)Communication Context Id (CCID) that Node B 101 should use in itsresponse to the NBAP RL Setup Request. The UTRAN CID Engine maintains amap that links the CCID to the AAL5 Call Id:

CCID-Call Id Map CCID AAL5 Call Id 4 bytes 8 bytes

Node B 101 responds to the NBAP RL Setup Request with a NBAP RL SetupResponse message, which includes the CCID and a Node B CommunicationContext Id (NBId). From that point on, the NBId is used by RNC 102 inall communication with Node B 101 for this call. Using the CCID, UTRANCID Engine does a lookup in the CCID-Call Id Map to identify the AAL5Call Id for the call. The AAL5 Call Id found in the CCID-Call Id Map isassigned to the NBAP RL Setup Response message. The UTRAN CID Enginealso maintains a map that links the NBId to the AAL5 Call Id:

NBId-Call Id Map NBId AAL5 Call Id 4 bytes 8 bytes

With the aid of the CCID and NBAP Call Id maps, all NBAP messages fromNBAP RL Setup to NBAP RL deletion will be assigned to the same AAL5 CallId. NBId and CCID are unique only per Node B, so a separate NBId-Call Idmap is maintained for each Node B.

Macro-Diversity and Micro-Diversity Handling

Micro-diversity is the addition of a radio link in the same Node B. Thisprocedure is initiated by a NBAP RL Addition Request, which includes thesame NBId as in the NBAP RL Setup Response message. So the UTRAN CIDEngine again uses the NBId to assign the AAL5 Call Id to the NBAP RLAddition Request messages. NBAP RL Addition Response messages have thesame CCID as in the NBAP RL Setup Request message and, therefore, arecorrelated in a similar fashion.

Macro-diversity is the addition of a radio link in a different Node B.This procedure is initiated by a NBAP RL Setup Request message. From theUTRAN CID Engine point of view, there is no difference between theaddition of the first radio link versus the addition of a 2^(nd) orN^(th) radio link because the signaling flow is exactly the same. Sincethe CCID-Call Id map and NBId-Call Id map are maintained per Node B, anynew radio link in a different Node B would involve adding new entries tothe CCID-Call Id and NBId-Call Id maps maintained for that Node B. Sincethe uplink scrambling code is still the same, the UTRAN CID Engine willassign the same AAL5 Call Id in all macro-diversity and micro-diversityscenarios.

Change of Uplink Scrambling Code

UE 106 operates in various service states depending on the type ofphysical channel that the UTRAN network has allocated. Transitionsbetween different states are based on inactivity timers and the amountof traffic that UE 106 or the UTRAN network wants to send. UE 106operates in Cell-DCH (Dedicated Channel) state to exchange relativelylarge amounts of data. In Cell-DCH state, a dedicated channel with anindividual code is assigned to UE 106. Data can be sent to and from UE106 without prior reservation of resources. For transmission ofrelatively small amounts of data, UE 106 transitions to Cell-FACH state,in which UE 106 sends receives data via the Random Access Channel (RACH)and Forward Access Channel (FACH). The RACH and FACH channels are sharedbetween several devices.

The NBAP procedures are used by RNC 102 to setup radio links and put UE106 into CELL-DCH state. Based on RRC measurement reports, the RNC maydelete all radio links and set UE 106 in CELL-FACH state. After a periodof time, RNC 102 may setup new radio links and UE 106 will be back inCELL-DCH state. This pattern of toggling back and forth between CELL-DCHand CELL-FACH state can happen very frequently when UE 106 is making aPS call. Every time UE 106 goes back to CELL-DCH state, it may beassigned a uplink scrambling code that is different than the last uplinkscrambling code it used. Because the AAL5 Call Id is based on the uplinkscrambling code, it is possible during a single PS call to have severalNBAP legs with each leg carrying a unique uplink scrambling code and,therefore, a unique AAL5 Call Id for each NBAP leg.

The UTRAN CID Engine only guarantees unique a AAL5 Call Id for the AAL5messages between the establishment of the first radio link and thetermination of the last radio link. Since the RRC leg of a call willcontain the uplink scrambling code changes, the UTRAN RRC manager—theAAL2 correlator—will provide information to combine all the legs of a PScall into a single call record.

ALCAP Protocol Correlation

ALCAP signaling begins with an Establishment Request (ERQ) messagefollowed by an Establishment Response (ECF) message by the receiver.Certain NBAP messages that establish a DCH-Id, such as the NBAP RL SetupResponse message, will have a Binding Id parameter for every DCH-Idbeing established. For every DCH-Id that is established, an ALCAP ERQmessage is sent with a Served User Generated Reference (SUGR) parameterthat exactly equals the Binding Id in the NBAP message for that DCH-Id.The ERQ message also has a Path Id/Channel Id combination thattranslates to a unique VPI/VCI/CID channel. This is the channel thatwill receive the AAL2 frames for that DCH-Id. This allows the presentinvention to established a correlation from the NBAP message thatinitiates the ALCAP to the various ALCAP messages and the AAL2 channelsthat have been setup. All of these may be tied to the same AAL5 Call Idusing a map.

The ALCAP protocol has two parameters, Originating Signaling AssociationId (OSAId) and Destination Signaling Association Id (DSAId), that aresimilar to the NBId and CCID parameters in the NBAP protocol.Accordingly, similar OSAId-AAL5 Call Id maps and DSAId-AAL5 Call Id mapsare setup per Node B. A mapping is also setup between the identifiedVPI/VCI/CID and the associated AAL5 Call Id. Any AAL2 frame on thatVPI/VCI/CID will be tagged with the associated AAL5 Call Id (or theuplink scrambling code) and the DCH-Id. The OSAId, DSAId, andVPI/VCI/CID maps are set up as follows:

OSAId-Call Id Map OSAId AAL5 Call Id 4 bytes 8 bytes

DSAId-Call Id Map DSAId AAL5 Call Id 4 bytes 8 bytes

VPI/VCI/CID - Call Id - DCH-Id Map VPI/VCI/CID AAL5 Call Id DCH-Id 8bytes 8 bytes 2 bytesWith the help of these maps the ALCAP legs and the established DCHchannels can be tied to a AAL5 Call Id.

RNSAP Protocol Correlation

RNSAP is transported via connection-oriented SCCP on IuR interface 105.The SCCP connection begins with SCCP Connection Request (CR) and SCCPConnection Confirmed (CC) messages followed by DT1 messages

IuR: SCCP CR (Source Local Reference=x); IuR: SCCP CC (Source LocalReference=y, Destination Local Reference=x);

IuR: SCCP DT1 (Destination Local Reference=y)-RNSAP Radio Link SetupRequest.

The messages in the RNSAP protocol are often the same as the NBAPprotocol messages, such as Radio Link Setup Request and Response. TheRNSAP Radio Link (RL) Setup Request message contains anuplink-scrambling code like the NBAP RL Setup Request message from whichthe AAL5 Call Id is generated. A map is then created which maintains themapping between the source local reference and the AAL5 Call Id as wellas the destination local reference and the AAL5 Call Id. This mapping ismaintained per RNC using the RNC point code (PC) that is present in theSCCP message.

Source Reference-Call Id Map RNC PC + Source Reference AAL5 Call Id 8bytes 8 bytes

Dest Reference-Call Id Map RNC PC + Dest Reference AAL5 Call Id 8 bytes8 bytes

The RNSAP RL Setup Response message contains DCH-Id and Binding Id as inthe NBAP RL Setup Response message. This is used to correlate the ALCAPprotocol messages and the dedicated AAL2 channels on IuR interface 105.

Data transmissions between Node B 101 and RNC 102 are defined bydedicated transport channel (DCH) frame protocol (FP) procedures on Iubinterface 104. In particular, the FP procedures define uplink (from aNode B to an RNC) and downlink (from an RNC to a Node B) data frames.Each uplink or downlink data frame comprises a header portion and apayload portion, which is also referred to as a protocol data unit(PDU), and supports multiplexing a number of DCHs in the payloadportion. Each DCH comprises Transport Blocks (TBs), which are the basicunits used to convey data. The size and number of TBs in each DCH of adata frame is identified by an associated transport format indicator(TFI) in the header portion of the data frame. The DCH FP proceduresalso apply to communications between RNCs 102 and 103 across Iurinterface 105.

Using the mappings illustrated above, the UTRAN CID Engine correlatesall NBAP, ALCAP and RNSAP messages that cross Iub and Iur interfaces 104and 105. The UTRAN CID Engine also associates every FP Data Frame on DCHto a AAL5 Call Id (or uplink scrambling code) and DCH-Id.

UTRAN RRC Manager—Call Correlation

FIG. 4 illustrates the relationship between UTRAN CID Engine 401, theAAL5 correlator, and UTRAN RRC Manager 402, the AAL2 correlator. UTRANRRC Manager 402 tracks the entire RRC leg of a call. It receives the rawAAL2 FP DATA frames from UTRAN CID Engine 401, which, as describedabove, will contain an AAL5 Call Id and DCH-Id if the frame was receivedon a DCH. UTRAN RRC Manager 402 performs the following functions:

-   -   Assign a unique Primary Call Id to every Transport Block that is        present in an AAL2 frame;    -   Associate every Transport Block to its corresponding Radio        Bearer Id (RB Id) with the help of DCH-Id;    -   Decipher the AAL2 frame with the assigned Primary Call Id and RB        Id;    -   Reassemble the AAL2 frame with the assigned Primary Call Id and        RB Id; and    -   Deliver the reassembled RRC Message with the Primary Call Id and        the optional AAL5 Call Id.        An AAL5 Call Id will be present if the FP DATA frame was        transmitted on a DCH. The AAL5 Call Id will be the Secondary        Call Id in the context of the UTRAN RRC Manager.

UTRAN RRC Manager 402 then forwards the RRC messages with Call Id toMaster Call Correlator 403. AAL5 messages are directly forwarded byUTRAN CID Engine 401 to Master Call Correlator 403. The Master CallCorrelation engine 403 then links the AAL2 and AAL5 legs together usingthe supplied Call Id information. UTRAN CID Engine 401, UTRAN RRCManager 402, and Master Call Correlator 403 are software applicationsthat may run on separate processors or on the same processor inmonitoring equipment 107. For example, monitoring equipment 107 maycomprise multiple blades, wherein each blade has a processor that iscapable of running one or more software applications, such as an AAL5correlation application, an AAL2 correlation application, and/or amaster call correlation application.

Primary Call Id Assignment

A Primary Call Id is assigned when UTRAN RRC Manager 402 receives an RRCConnection Request message in case of a mobile-originated call orreceives a paging message in case of a mobile-terminated call. UE 106 isidentified by means of the UE-Id that is present in both these messages.The Primary Call Id is generated for either of these messages using theRNC-Id and the time when that message was received. The format of thePrimary Call Id is as follows:

Primary Call Id Structure RNC-Id Current Time Stamp (Seconds) SequenceNumber (0-65535) 4 bytes 4 bytes 2 bytes

The two-byte Sequence Number is simply a running counter that isincremented by 1 every time a Call Id is assigned and wraps back to 0when it reaches 65535. This means that as many as 65536 calls can behandled per second by UTRAN RRC Manager 402 by assigning each of them aunique Primary Call Id.

UTRAN RRC Manager 402 tracks a call by maintaining several keys in a mapor hash table. For every call, the following identifiers must be trackedand associated with the call:

-   -   Uplink Scrambling Code—may change during a call, so specific RRC        messages are analyzed to see if such a change is present;    -   Control Radio Network Temporary Identity (CRNTI)—can change        during a call and the changes are tracked continuously; and    -   UTRAN Radio Network Temporary Identity (URNTI).

UTRAN RRC Manager 402 takes the following actions to assign the PrimaryCall Id upon receiving various RRC messages.

Upon receipt of an RRC Connection Request message, UTRAN RRC Manager 402creates a Primary Call Id and associates it with the UE-Id in themessage by creating a UEId-Call Id Map as follows:

UEId-Primary Call Id Map UE-Id Type UE-Id Primary Call Id 2 bytes 8bytes 10 bytes

Upon receipt of an RRC Connection Setup message, using the UE-Id in themessage, UTRAN RRC Manager 402 gets the Primary Call Id from theUEId-Primary Call Id Map. UTRAN RRC Manager 402 also extracts otherparameters from the message, such as a URNTI, CRNTI, and the uplinkscrambling code and creates a URNTI-Call Id Map, CRNTI-Call Id Map, andUplink Scrambling Code (ULS)-Call Id Map as follows:

ULS-Primary Call Id Map RNC-Id Uplink Scrambling Code (ULS) Primary CallId 4 bytes 4 bytes 10 bytes

CRNTI-Primary Call Id Map Cell Id CRNTI Primary Call Id 4 bytes 4 bytes10 bytes

URNTI-Primary Call Id Map URNTI Primary Call Id 4 bytes 10 bytes

For AAL2 frames on a DCH channel, UTRAN RRC Manager 402 uses the UplinkScrambling Code or AAL5 Call Id in the message to lookup the PrimaryCall Id in the ULS-Call Id Map.

For RRC messages that transition UE 106 from Cell-DCH state to Cell-FACHstate, UTRAN RRC Manager 402 gets the Primary Call Id from theULS-Primary Call Id Map and deletes that ULS entry from the map since UE106 is now in CELL_FACH state. Using the CRNTI in the message, UTRAN RRCManager 402 adds an entry to the CRNTI-Primary Call Id Map. Since CRNTIis unique only per cell, the Cell Id is included as a key with CRNTI.The Cell Id is derived from the primary scrambling code in the message.

For RRC messages that transition UE 106 from Cell-FACH state to Cell-DCHstate, UTRAN RRC Manager 402 gets the Primary Call Id using the CRNTI orURNTI in the message and by doing a look up into the appropriate map.UTRAN RRC Manager 402 also invalidates the CRNTI entry and adds an entryto the ULS-Primary Call Id Map. The message will contain a new uplinkscrambling code since it transitioned to Cell-DCH mode.

Upon receiving an RRC Connection Release Complete message, UTRAN RRCManager 402 invalidates and deletes all entries related to the call.Accordingly, UTRAN RRC Manager 402 handles the following scenarios incall tracking and assigns the same unique Primary Call Id until UE 106terminates the call:

-   -   Cell-DCH to Cell-FACH transition with Cell update;    -   Cell-DCH to Cell-FACH transition without Cell update;    -   Cell-DCH to Cell-FACH and back to Cell-DCH transition with the        same uplink scrambling code;    -   Cell-DCH to Cell-FACH and back to Cell-DCH transition with a        different uplink scrambling code; and    -   Cell-FACH to Cell-DCH transition.

A class diagram for an embodiment of UTRAN RCC Manager 402 isillustrated in FIG. 5, which shows examples of the software modules anddata structures that can be used to implement an AAL2 correlationengine.

Radio Bearer Id (RB Id) Assignment

An RB Id needs to be assigned to each transport block (TB) that istransmitted on a DCCH or DTCH channel to identify the logical channel towhich the TB belongs. In addition, a Primary Call Id needs to beassigned to the TB. The primary reason for assigning an RB Id is becausethe RB-Id is used as a parameter to decipher the signal unit, ifciphering is enabled, and to reassemble the deciphered signal unit sinceRLC reassembly is done per UE per RB Id per direction. The RB Id mappingis obtained from the RRC Connection Setup, Radio Bearer Setup, and RadioBearer Reconfiguration messages. Once this mapping is stored, the RB-Idfor each TB can be determined using the DCH-Id that it carries if the TBis on a DCH channel. If the TB is on a RACH or FACH channel, the C/Tfield in the MAC header is used to get the RB Id.

Deciphering

To decipher AAL2 Transport Blocks on the IuB and IuR interfaces, thedeciphering key (CK) needs to be associated with the Primary Call Id.The CK is obtained from the IuCs or IuPs interfaces depending on whetherthe call established in the CS Domain or PS Domain. The IuCs and IuPsinterfaces connect the RNCs to the UMTS Core Network. The CK can also betied to UE-Id, because the UE-Id parameter is present when a call isestablished on the IuPs or IuCs interface.

Once the UTRAN RRC Manager receives the CK along with the UE-Id, the CKcan be tied to a Primary Call Id using the UEId-Primary Call Id Map.Accordingly, for any AAL2 Transport Block that carries a Primary CallId, the UTRAN RRC Manager can obtain the corresponding CK to use fordeciphering the TB.

RLC/MAC Reassembly Engine

The Radio Link Control/Medium Access Control (RLC/MAC) protocolReassembly Engine reassembles FP Transport Blocks received from theUTRAN CID Engine into RLC service data units (SDUs) in three RLC Modes:Transparent, Acknowledged, and Unacknowledged mode. FIG. 6 illustrateshow RLC/MAC Reassembly Engine 601 and decipher application 602 fits intothe packet processing flow of the UTRAN monitoring equipment. RLC/MACReassembly Engine 601 and decipher application 602 may be embodied asseparate applications within UTRAN RRC Manager 402.

AAL2 frame 61 includes Transport Blocks that have been sent overdifferent logical channels, DCH1 and DCH2, by the UE. The blocks fromchannels DCH1 and DCH2 are combined into FP frame 61 by UTRAN CID Engine401 and sent to UTRAN RRX Manager 402. Decipher application 602deciphers FP frame 61 into deciphered frame 62. The Transport Blocks offrame 62 comprise MAC PDUs 63, which in turn comprise RLC PDUs 64.RLC/MAC Reassembly Engine 601 processes and reassembles the data in RLCPDUs 64 into SDUs 65. When a complete SDU 65 is reassembled, RLC/MACReassembly Engine 601 and UTRAN RRC Manager 402 sends the SDU forfurther processing by Master Call Correlator. RLC/MAC Reassembly Engine107 provides the following functions:

-   -   Tracking the RLC reassembly process for individual logical        channel instances, which are identified by RB Id, for different        UEs, which are identified by the Primary Call Id, and tracking        the RLC reassembly process for common logical channel instances;    -   Reassembly in RLC Transparent Mode, segmented and non-segmented;    -   Reassembly in RLC Unacknowledged and Acknowledged Mode, with the        handling of segmentation, concatenation, and padding, and        out-of-sequence arrival;    -   Handling missing fragment detection via sequence number check,        in Unacknowledged mode;    -   Handling missing fragment detection, duplicate detection,        out-of-window size arrival in Acknowledged mode;    -   Handling RLC RESET and STATUS protocol control in Acknowledged        mode;    -   Handling macro-diversity or soft handover in which duplicate        frames are received on multiple IuB/IuR connections; and    -   Handling channel type switching, in which case the RLC Packet        Data Units (PDUs) that make up an RLC SDU could come from        different transport channels, such as RACH, FACH, and DCH.        RLC/MAC Reassembly Engine 601 is independent of the transport        channel since every frame has a Primary Call Id and the RB Id        assigned to it.

FIG. 7 illustrates the static data architecture of RLC/MAC ReassemblyEngine 601. RLC/MAC Reassembly Engine 601 uses hierarchical datastructures to keep track of RLC PDUs arriving on different channels formultiple users. RLC Reassembly Engine 701 is an instance of the RLCReassembly Engine software. Each instance of RLC Reassembly Engine 701has multiple instances of UE Reassembly 702 to keep track of individualactive users. Each instance of UE Reassembly 702 is identified by aunique Primary Call Id. Each UE Reassembly instance 702 has multipleinstances of ChannelReasmProcess 703 to keep track of the RLC reassemblyprocesses for different logical channel instances for that user. Eachinstance of ChannelReasmProcess 703 is identified by a logical channelkey, which consists of two elements: (1) Direction (i.e. uplink ordownlink), and (2) RB Id, which may be a signaling Radio Bearer Id orlogical channel instance Id. Each ChannelReasmProcess 703 has multipleinstances of PDU Buffer 704 to keep track of the PDU fragments for aparticular logical channel's RLC reassembly process. Each PDU Buffer 704is identified by a Sequence Number (SN) of a PDU.

A class diagram of RLC/MAC Reassembly Engine 601 is illustrated in FIG.8, which shows examples of the software modules and data structures thatcan be used to reassemble SDUs.

Macro-Diversity Handling of IuB/IuR Soft Handover

In the soft handover scenario illustrated in FIG. 9, the same frame issent by UE 901 on multiple radio links. At position 1, frame 91 iscommunicated between UE 901 and RNC 902 only via Node B 903 and Iubinterface 904. As UE 901 moves to position 2, it begins a soft handoveroperation from Node B 903 to Node B 905. At position 2, frame 92 iscommunicated between UE 901 and RNC both via Node B 903 and Iubinterface 904 and via Node B 905 and Tub interface 906. As the softhandover is completed, UE 901's only radio link is with Node B 905 atposition 3. Accordingly, at position 3, frame 93 is communicated betweenUE 901 and RNC 902 only via Node B 905 and Iub interface 906.

As a result of this handover, frames 92 for the same call on UE 901 maybe captured by monitoring equipment from two routes at the same time.UTRAN RRC Manager 402 eliminates these duplicates by assigning the samePrimary Call Id and RB Id to these duplicate frames 92. When multipleframes 92 reach RLC Reassembly Engine 601, they each go into the samePDU Buffer 704 because each of the duplicate frames have the same theRLC sequence number. RLC Reassembly Engine 601 takes the firsterror-free frame and discards the rest as duplicates. UTRAN RRC Manager402 is able to handle IuB/IuR Soft Handover using its Primary Call Idand RB-Id tracking logic.

Monitoring equipment 107 captures all messages for all UEs and uses thePrimary Call Id and the AAL5 Call Id (or Secondary Call Id) to identifymessages belonging to each call for the UEs. Monitoring equipment 107combines messages having the same Primary Call Id and AAL5 Call Id intocall records per UE per call. The call records contain the SDUs for thecall and allow an operator to evaluate the call for quality of service,call type, call length and other performance indicators.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. For example,many of the features and functions discussed above can be implemented insoftware, hardware, or firmware, or a combination thereof. As anotherexample, it will be readily understood by those skilled in the art thatthe format of the various mappings and identifiers described herein maybe varied while remaining within the scope of the present invention.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

1. A method for correlating data in a radio access network, comprising:capturing data passing to and from a first radio network controller;identifying ATM Adaptation Layer type 5 (AAL5) frames within the data;assigning a first call identifier to the AAL5 frames; identifying ATMAdaptation Layer type 2 (AAL2) frames within the data; assigning asecond call identifier to the AAL2 frames; and combining AAL2 frames andAAL5 frames having a same first call identifier and a same second callidentifier into a call record.
 2. The method of claim 1, wherein thedata passing to and from the first radio network controller comprisesdata passing over an Iub interface between a Node B and the first radionetwork controller.
 3. The method of claim 1, wherein the data passingto and from the first radio network controller comprises data passingover an Iur interface between the first radio network controller and asecond radio network controller.
 4. The method of claim 1, wherein thecall record comprises service data units (SDUs) associated with a singlecall.
 5. The method of claim 1, further comprising: deciphering the AAL2frames; and reassembling service data units (SDUs) carried in the AAL2frames.
 6. The method of claim 1, wherein capturing data passing to andfrom a first radio network controller further comprises: capturing datapassing from the first radio network controller to a first base stationthat is in communication with user equipment; and capturing data passingfrom the first radio network controller to a second base station that isin communication with the user equipment.
 7. The method of claim 6,wherein the first radio base station and the second radio base stationare in communication with the user equipment at the same time.
 8. Asystem for correlating data in a radio access network, comprising: afirst correlation engine coupled to interfaces between components of theradio access network, wherein the first correlation engine receives ATMAdaptation Layer type 2 (AAL2) frames and ATM Adaptation Layer type 5(AAL5) frames from the interfaces; a second correlation engine coupledto the first correlation engine, wherein the second correlation enginereceives AAL2 frames from the first correlation engine; and a thirdcorrelation engine coupled to both the first and second correlationengines, wherein the third correlation engine receives AAL5 framesmapped to a first call identifier from the first correlation engine andreceives AAL2 frames mapped to a second call identifier from the secondcorrelation engine.
 9. The system of claim 8, wherein the secondcorrelation engine further comprises: a decipher engine, wherein thedecipher engine decodes and deciphers the AAL2 frames; and a reassemblyengine, wherein the reassembly engine assembles data carried in the AAL2frames into service data units (SDUs).
 10. The system of claim 8,wherein the first correlation engine maps parameters of a Node BApplication Part (NBAP) protocol to the first call identifier.
 11. Thesystem of claim 8, wherein the first correlation engine maps parametersof a Access Link Control Application Part (ALCAP) protocol to the firstcall identifier.
 12. The system of claim 8, wherein the firstcorrelation engine maps parameters of a Radio Network SubsystemApplication Part (RNSAP) protocol to the first call identifier.
 13. Thesystem of claim 8, wherein the second correlation engine maps parametersof a Radio Resource Control (RRC) protocol to the second callidentifier.
 14. The system of claim 8, wherein the first correlationengine is coupled to Iub and Iur interfaces in a UMTS Terrestrial RadioAccess Network (UTRAN).
 15. A computer-readable medium havingcomputer-executable instructions for combing data associated with callsin a radio access network, said computer-executable instructionscomprising: means for capturing data from the radio access network;means for identifying ATM Adaptation Layer type 5 (AAL5) frames withinthe data; means for assigning a first call identifier to the AAL5frames; means for identifying ATM Adaptation Layer type 2 (AAL2) frameswithin the data; means for assigning a second call identifier to theAAL2 frames; and means for combining AAL2 frames and AAL5 frames havinga same first call identifier and a same second call identifier into acall record.
 16. A computer-readable medium having computer-executableinstructions as recited in claim 15, wherein the means for capturingdata from the radio access network further comprises: means forcapturing data passing to and from a radio network controller over oneor more Tub interfaces and one or more Iur interfaces in the radioaccess network.
 17. A computer-readable medium havingcomputer-executable instructions as recited in claim 15, wherein thecall record comprises service data units (SDUs) associated with a singlecall.
 18. A computer-readable medium having computer-executableinstructions as recited in claim 15, further comprising: means fordeciphering the AAL2 frames; and means for reassembling service dataunits (SDUs) carried in the AAL2 frames.
 19. A computer-readable mediumhaving computer-executable instructions as recited in claim 15, furthercomprising: means for capturing data passing from a first base stationin the radio access network to user equipment; and means for capturingdata passing from second base station in the radio access network to theuser equipment.
 20. A computer-readable medium havingcomputer-executable instructions as recited in claim 15, wherein themeans for assigning a first call identifier maps parameters of a Node BApplication Part (NBAP) protocol to the first call identifier.
 21. Acomputer-readable medium having computer-executable instructions asrecited in claim 15, wherein the means for assigning a first callidentifier maps parameters of a Access Link Control Application Part(ALCAP) protocol to the first call identifier.
 22. A computer-readablemedium having computer-executable instructions as recited in claim 15,wherein the means for assigning a first call identifier maps parametersof a Radio Network Subsystem Application Part (RNSAP) protocol to thefirst call identifier.
 23. A computer-readable medium havingcomputer-executable instructions as recited in claim 15, wherein themeans for assigning a second call identifier maps parameters of a RadioResource Control (RRC) protocol to the second call identifier.